Ετήσια αρχεία: 2023

How to Free Space from /var/log by Removing Old Log Files

 στο GNU/Linux  επισημασμένο με ετικέτα /var/log/ / free space / GNU/Linux / ubuntu Από

Introduction

Managing disk space is a critical task for system administrators and users alike. In Linux systems, the /var/log directory can become a source of space consumption due to the accumulation of log files. In this post, we’ll explore a simple command to free up space by deleting old compressed log files and discuss its pros and cons.

The Command

The command find /var/log -type f -name "*.gz" -delete is a powerful way to clean up space in the /var/log directory. Here’s a breakdown of what this command does:

  • find /var/log: Searches in the /var/log directory.
  • -type f: Restricts the search to files.
  • -name "*.gz": Looks for files ending with .gz, which are typically compressed log files.
  • -delete: Deletes the files that match the search criteria.

Pros

  1. Efficient Space Management: This command quickly frees up disk space consumed by old, compressed log files, which is essential for the smooth functioning of the system.
  2. Automatable: The command can be automated through a cron job or a script, making regular maintenance easier.
  3. Selective Deletion: It specifically targets .gz files, which are usually older log files that have been compressed, thus keeping the most recent logs intact.

Cons

  1. Potential Data Loss: Important historical data in the log files could be lost if they are deleted without proper review.
  2. Lack of Control Over File Age: This command does not discriminate based on the age of the log files. It deletes all .gz files, regardless of how recently they were compressed.
  3. No Backup: The command executes a direct deletion without creating backups, which could be problematic if a file is deleted accidentally.

Best Practices

  • Review Files Before Deletion: Run the command without the -delete flag first to review which files will be deleted.
  • Implement Log Rotation: Set up log rotation to manage log files systematically, compressing and archiving older logs while deleting the oldest ones.
  • Backup Important Logs: Always keep a backup of important logs before running any deletion command.

Conclusion

While the command find /var/log -type f -name "*.gz" -delete is an effective way to free up space in the /var/log directory, it’s important to use it judiciously. Understanding its pros and cons helps in making informed decisions about log management in a Linux environment.

How to speed up Youtube videos more than 2x

 στο Applications  επισημασμένο με ετικέτα browser / console / speed / youtube Από

Using the playbackRate command to adjust video playback speed on YouTube slightly differs from using it on a standard HTML video element. This is because YouTube uses its player interface, built on top of the HTML5 video API but includes additional features and customizations.

Here’s a step-by-step guide on how to use the playbackRate command on YouTube:

Open YouTube and Select a Video: Navigate to YouTube and open the video you want to adjust.

Access the Browser Console:

  • Open Developer Tools in your browser. This is usually done by right-clicking on the page and selecting “Inspect,” or by pressing Ctrl+Shift+I (Windows/Linux) or Cmd+Option+I (Mac).
  • Switch to the “Console” tab.

Use the Correct JavaScript Command:

  • On YouTube, the video player element can be accessed differently. The command to adjust the playback speed might look like this:
  • document.querySelector('video').playbackRate = X;
  • Replace X with the desired playback speed. For example, 1.5 for 1.5x speed, or 0.75 for 75% of the normal speed.
document.querySelector('video').playbackRate = X;

For regular use, the built-in speed settings in the YouTube player (accessible via the gear icon in the player controls) are the recommended and easiest method to change playback speed. They provide a range of speed options in a user-friendly manner without the need for coding or console commands.

Understanding the playbackRate Command in JavaScript

document.getElementsByTagName("video")[0].playbackRate = X;

In the dynamic world of web development, JavaScript stands as a cornerstone technology, enabling developers and users to interact with web content in powerful ways. Among its many features is the ability to control video playback on web pages. This blog post delves into one such aspect: using the playbackRate command to control the speed of video playback.

What is playbackRate?

The playbackRate property in JavaScript is a feature of the HTML5 Video API. It allows developers to change the speed at which a video plays on a web page. The command document.getElementsByTagName("video")[0].playbackRate = X; is a practical implementation of this feature.

Breaking Down the Command

  • document: This is the root node of the HTML document.
  • getElementsByTagName("video"): This method returns a live HTMLCollection of elements with the specified tag name, in this case, “video”.
  • [0]: Since getElementsByTagName returns a collection, [0] accesses the first video element in the collection. If there are multiple videos, changing the index accesses different videos.
  • playbackRate: This property sets or returns the current playback speed of the video. 1 is the normal speed, values greater than 1 increase the speed, and values between 0 and 1 slow it down.
  • X: This represents the desired playback speed. For instance, setting X to 1.5 would make the video play at 1.5 times its normal speed.

Practical Use Cases

  • Educational Content: Speed up or slow down instructional videos to match the learner’s pace.
  • Accessibility: Adjust video speed for viewers who need more time to process visual content.
  • Entertainment: Speed through slow sections of videos or slow down for detailed analysis of scenes.

How to Implement

  1. Identify the Video: Ensure the video element is correctly targeted, especially in pages with multiple videos.
  2. Set the Playback Speed: Assign the desired speed to playbackRate. For example, document.getElementsByTagName("video")[0].playbackRate = 1.5; speeds up the first video by 50%.
  3. Test and Debug: Verify that the speed adjustment works across different browsers and devices.

Best Practices

  • User Control: Ideally, provide a user interface for viewers to adjust the speed according to their preference.
  • Browser Compatibility: Test the functionality in various browsers to ensure consistent behavior.
  • Fallbacks: In cases where playbackRate is not supported, consider alternative methods or inform the user.

Conclusion

The playbackRate property in JavaScript offers a simple yet powerful tool for enhancing the video viewing experience on web pages. By understanding and utilizing this command, developers can provide more dynamic and user-friendly web applications. Whether it’s for educational purposes, accessibility, or just personal preference, the ability to control video playback speed is an invaluable feature in today’s web landscape.

How to Create a WiFi Hotspot in Ubuntu 22.04

 στο GNU/Linux  επισημασμένο με ετικέτα ffmpeg / GNU/Linux / hotspot / nmcli / ubuntu / wi-fi Από

Creating a WiFi hotspot on Ubuntu 22.04 is a straightforward process that can be very useful for sharing your internet connection with other devices. Turning your Ubuntu machine into a WiFi access point is a handy solution, whether at home or in a setting where a traditional WiFi network isn’t available. Here’s a detailed guide on configuring WiFi Access Points using the network-manager snap.

Prerequisites

Before we begin, ensure that you have the following:

  • A computer running Ubuntu 22.04.
  • A wireless network interface on your Ubuntu device.
  • The network-manager snap installed on your system.

Step-by-Step Guide to Create a WiFi Hotspot

Open the Terminal: First, open your terminal. You can do this by pressing Ctrl + Alt + T or searching for ‘Terminal’ in your applications menu.

Identify Your WiFi Interface: You need to know the name of your WiFi network interface. You can find this by running the command nmcli device status. Look for the device under the “DEVICE” column that has “wifi” listed in the “TYPE” column.

Configure the WiFi Hotspot: Use the following command to set up your WiFi hotspot:php

nmcli d wifi hotspot ifname <wifi_iface> ssid <ssid> password <password>;

Replace <wifi_iface> with your WiFi interface name, <ssid> with your desired network name (SSID) and <password> with your chosen password. Remember, the password should be between 8-63 characters or 64 hexadecimal characters.

For example, if your WiFi interface is wlan0, your desired SSID is MyHotspot, and your password is MyStrongPassword123, the command will look like this:

Connection Verification: If the command is successful, network-manager will create a connection named ‘Hotspot <N>’, where <N> is a number. This indicates your hotspot is active.

Shared Internet Connection: The created hotspot offers a shared connection by default. This means any device connected to your hotspot should be able to access the internet if your Ubuntu device has internet access.

Connecting Devices: Search for available WiFi networks on your other devices (like smartphones or laptops). You should see the SSID you set (MyHotspot in our example). Connect to it using the password you configured.

Tips and Considerations

  • Ensure your device has a stable internet connection if you intend to share it via the hotspot.
  • Keep your hotspot secure by using a strong, unique password.
  • Remember that using your computer as a hotspot may impact its battery life more quickly if not plugged in.

Conclusion

Creating a WiFi hotspot on Ubuntu 22.04 is a useful feature, especially when you need to share your internet connection quickly and efficiently. Following these simple steps, you can turn your Ubuntu machine into a reliable WiFi access point for various devices.

ncmli device wifi hotspot [ifname ifname] [con-name name] [ssid SSID] [band {a | bg}] [channel channel] [password password]
   Create a Wi-Fi hotspot. The command creates a hotspot connection profile according to Wi-Fi device capabilities and activates it on the device. The hotspot is secured with WPA if device/driver supports that, otherwise WEP is used. Use connection down or device down to stop the hotspot.

   Parameters of the hotspot can be influenced by the optional parameters:

   ifname
       what Wi-Fi device is used.

   con-name
       name of the created hotspot connection profile.

   ssid
       SSID of the hotspot.

   band
       Wi-Fi band to use.

   channel
       Wi-Fi channel to use.

   password
       password to use for the created hotspot. If not provided, nmcli will generate a password. The password is either WPA pre-shared key or WEP key.

       Note that --show-secrets global option can be used to print the hotspot password.
       It is useful especially when the password was generated.

How to Run Three Instances of Signal on Ubuntu

 στο GNU/Linux  επισημασμένο με ετικέτα apt / signal beta / signal desktop / snap / ubuntu Από

Signal is a popular, privacy-focused messaging app. For various reasons, you might want to run multiple instances of Signal on your Ubuntu system. Here, we’ll guide you through the process of installing three different versions of Signal: the Snap package, the standard Debian-based installation, and the Signal Beta for Linux.

Prerequisites

  • Ubuntu OS (We recommend a recent version, like 20.04 or later)
  • Basic understanding of Linux terminal commands

1. Installing Signal from Snap

Snap is a package management system that makes it easy to install applications in Linux. Follow these steps to install Signal using Snap:

  1. Open Terminal: Use Ctrl+Alt+T to open the terminal.
  2. Install Signal: Enter the command: sudo snap install signal-desktop.
  3. Launch Signal: You can find Signal in your applications menu or launch it from the terminal with signal-desktop.

2. Installing Signal Using Linux (Debian-based) Install Instructions

For the second instance, we will use the Debian-based installation method (https://signal.org/download/):

  1. Add Signal’s Official Repository:
    • Open Terminal.
    • Enter:
      wget -O- https://updates.signal.org/desktop/apt/keys.asc | gpg --dearmor > signal-desktop-keyring.gpg;
      cat signal-desktop-keyring.gpg | sudo tee /usr/share/keyrings/signal-desktop-keyring.gpg > /dev/null;
    • Add the repository:
      echo 'deb [arch=amd64 signed-by=/usr/share/keyrings/signal-desktop-keyring.gpg] https://updates.signal.org/desktop/apt xenial main' | sudo tee /etc/apt/sources.list.d/signal-xenial.list;
  2. Update and Install Signal:
    • Update package database: sudo apt update.
    • Install Signal: sudo apt install signal-desktop.
  3. Launch the Application: Find Signal in your application menu or type signal-desktop in the terminal.

3. Installing Signal Beta for Linux (Debian-based)

Finally, let’s install the Beta version (https://support.signal.org/hc/en-us/articles/360007318471-Signal-Beta):

  1. Add Signal Beta Repository:
    • Open Terminal.
    • Enter:
      wget -O- https://updates.signal.org/desktop/apt/keys.asc | gpg --dearmor > signal-desktop-keyring.gpg;
      cat signal-desktop-keyring.gpg | sudo tee -a /usr/share/keyrings/signal-desktop-keyring.gpg > /dev/null;
    • Add the Beta repository:
      echo 'deb [arch=amd64 signed-by=/usr/share/keyrings/signal-desktop-keyring.gpg] https://updates.signal.org/desktop/apt xenial main' | sudo tee -a /etc/apt/sources.list.d/signal-xenial.list
  2. Update and Install Signal Beta:
    • Update the system: sudo apt update.
    • Install Signal Beta: sudo apt install signal-desktop-beta.
  3. Launch Signal Beta: It should appear in your applications menu or can be started from the terminal with signal-desktop-beta.

Tips for Managing Multiple Instances

  • Different Profiles: Each instance of Signal will require a different phone number for registration.
  • System Resources: Running multiple instances can consume more system resources. Monitor your system’s performance.
  • Updates: Regularly check for updates to each version to ensure security and functionality.

Conclusion

With these steps, you should now have three different versions of Signal running on your Ubuntu system. This setup is ideal for separating personal, work, and testing environments within the same machine. Enjoy your enhanced and versatile messaging experience!